Results of todays trip to the range
Shooting a Cooper Model 22 in 22-250AI after market BBL ( 26" Rock River 5R 8" twist) 44.9 grs of H4831SC produced an average MV of 3,600 pushing Sierra 65gr Game king gave me a 1/2 " group at 100yards off sand bag and rear rest. Might add with that specific model Cooper I have, A shooter has to rest that forearm over the sand bags right at the checkering are you'll have a group that looks like a mini buck shot pattern. Also fired 55gr Sierra Blitzking in front of 44grs of WW-760 that produced 3,900 average and under 1/2 " group. Now for a curve ball Gunsmith that installed this after market BBL had a 2nd chance to run a bore scope.( After I shot Aprox 500 rnd through it) He mentioned I have sever throat erosion. But its still shoots great for a sporter weight BBL.